Rik Van Steenbergen was one of 'the two Riks' - the other being Rik Van Looy - Belgian cyclists who were major figures in bike racing in the 1950s. Rik Van Steenbergen was 'Big Rik', you guessed it, due to his size. He was a phenomenally successful Classics rider who was World Road Race Champion on three occassions, 1949, 1956 and 1957. Wikipedia comments that "it is estimated Van Steenbergen won slightly fewer than 1000 races" in his career.
He was less successful in the Grand Tours - winning a hatful of stages but never winning the General Classification. Many commentators have put this lack of success down to a single factor - money. The one day races simply paid better than the multi-stage tours - so that is where Rik's priorities lay.
After he retired his life became even more colourful. He became a gambling addict, spent time in jail and starred in a Belgian porn movie as Dimitri, an amorous Greek fisherman. Chris Froome, he wasn't.
This, probably hand-tinted, image shows a rather contented Rik Van Steenbergen, riding for the Mercier team, possibly in 1954, and using a Simplex Tour de France derailleur.
I believe that Riv Van Steenbergen also won his 1949 World Road Race Championship riding a Simplex Tour de France derailleur, and used a Simplex Juy 543 in 1956 and 1957.